After another few years of (casual) work, XDM is back in very good shape!
It's quite stable, and quite fun to play (confirmed by summer lan-party testing). List of game rules include: free for all, teamplay, capture the thing, domination, and...
Suddenly, co-operative appears! Not very complete at this precise moment, but more than just playable. With bots (which are a little bit more intelligent... and lethal by now)!

(no, bots don't talk to triggers anymore :) )

Main difference from other mods is: XDM doesn't need special maps or offline map copying or patching - everything is done by small scripts or the code itself.

Also, XDM is now not only multiplayer, but a good single-player platform, featuring full Half-Life and basic Spirit of Half-Life compatibility.

Still no questline, but I guess it's not that important right now (^_^). Anyway, author of The Monorail Quest proposed cooperation in mapping, so there are some different possibilities...

Change log of recent testing release (once in 3 months):

> More gameplay combos!
> Game skill level affects monsters in more ways: health, turn speed and reaction.
> XBM: bots behaviour is a little bit more accurate (shooting skills, ability to duck, other).
> XBM: bots will whine about loosing the game. Winner will boast :)
> Spirit of Half-Life compatible entities: multi_switcher, multi_watcher
> Dev: 'checkpoint' for info_player_* which works like 'master' except each player must 'collect' checkpoints. Right now trigger_autosave works as checkpoint.
> Dev: 'master' trigger_gravity, trigger_multiple, func_ladder
> Dev: sv_generategamecfg 1/0 - generate game.cfg for HL protocol 47+ games (uses settings.scr)
> Dev: very convinient on-the-fly map patching and configuration system (ENT, CFG files and entity values)
> Weapon highlighting in the dark (on ground).
Improved:
> multi_manager now has SoHL-compatible flags (loop, once, start) and maximum of 32 targets.
> Map graph generation is now faster and .nrp files are only created when "developer" is set to 2.
Fixed:
> Awards for using func_tank* work properly.
> Valve-made memory leak in client dll (VGUI).
> Grenade mode text is now really taken from titles.txt.
Changed:
> Buttons no longer play "pressed" sounds when locked.

Some technical details: XDM modular engine now detects Half-Life protocol version or even Xash3D and tunes itself accordingly - the only thing XDM cannot be ran under is HL1015- :)
Player model format was not changed (there were some requests for additional animations and blending) so your hundreds of HL DM models will be put to good use!
As usual, more screenshots and updates @official site